Chicago & Illinois Western Railway Bridge

The Chicago & Illinois Western Railway Bridge is a rare-surviving example of a patented bridge design by Theodor Rall. Although this bridge type was invented by Rall, the patent was held by the contractor, Strobel Steel Construction Company of Chicago. The Rall type was one of the designs most frequently used by the railroads in the early twentieth century and is significant for combining the bascule bridge technologies of both rolling and trunnion motion. The bridge is a single track, single-leaf bascule span which runs on an east-west axis over a slip in the Chicago Sanitary and Ship Canal. This low-profile bridge is supported by three unevenly-spaced piers made from reinforced concrete. Visible struts are located on the sides of the bridge along with a trunnion, which when engaged by an electric motor, pulls the leaf up and rolls it back wards along the horizontal track girders. Today, the bridge's mechanism has been disabled and it remains in fixed position.